102 Remarks on the Cretaceous and [February, 



REMARKS ON THE CRETACEOUS AND TERTIARY 

 FLORA OF THE WESTERN TERRITORIES. 



THE following notes were suggested by two valuable commu- 

 cations to Nature, in the numbers bearing date June 30 and 

 October 6, 1881 ; the first, that of Dr. J. S. Newberry, tending to 

 show that the flora of the Dakota group, together with that of 

 the Laramie group, are of Cretaceous age ; the second, that of J. 

 Starkie Gardner, Esq., of London, contending to the contrary, 

 that both those floras are Tertiary. 



As there is not any fixed characters admitted as standard 

 points of determination of the age of a fossil flora, phytopalaeon- 

 tologists have no means of coming to an understanding on the 

 subject, except by a comparison of the vegetable remains of the 

 divers formations with those of localities whose geological hori- 

 zon has been ascertained. 



I take here, for comparison with the plants of the Dakota 

 group, the Upper Cretaceous flora of Groenland, Atane ; that of 

 Moletin, of Quedlinburg, of the Quader-sandstone of the Hartz 

 and other localities of Germany where this formation, generally 

 considered as Middle Cretaceous, or Cenomanian, has been 

 observed. 



One hundred and seventy specific forms of plants are now 

 known from the Dakota group; they represent six ferns, one 

 Equisetum, or seven cryptogamous acrogens ; seven Cycadea;, 

 ten conifers, three monocotyledonous plants ; the others, about 

 one hundred and fifty, all dicotyledonous angiosperms. 



As far as known until now, the flora of Atane, Groenland, is 

 represented in sixty-three species — thirteen ferns, two Cycadese, 

 ten conifers, three monocotyledonous, while thirty-four, or a little 

 more than one-half, are angiosperms. 



The relation of the Atane flora with that of the Dakota group 

 is marked by ten identical species : one fern, two conifers and 

 seven dicotyledonous ; while quite as distinct an affinity is demon- 

 strated by allied types of the genera Ficus, Sassafras, Diospyros 

 and Sapindus. 



The flora of Quedlinburg is composed of twenty species; four 

 ferns, four conifers, one monocotyledonous, with eleven angio- 

 sperms, a little more than half of the species. Of this group of 



